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Full-Text Articles in Physical Sciences and Mathematics
Chromospherically Active Stars. Xi. Giants With Compact Hot Companions And The Barium Star Scenario, Francis C. Fekel, Gregory W. Henry, Michael R. Busby, Joseph J. Eitter
Chromospherically Active Stars. Xi. Giants With Compact Hot Companions And The Barium Star Scenario, Francis C. Fekel, Gregory W. Henry, Michael R. Busby, Joseph J. Eitter
Information Systems and Engineering Management Research Publications
We have determined spectroscopic orbits for three chromsopherically active giants that have hot compact companions. They are HD 160538 (KO III + wd, P = 904 days), HD 165141 (G8 III + wd, P approximately 5200 days), and HD 185510 (KO III + sdB, P = 20.6619 days). By fitting an IUE spectrum with theoretical models, we find the white dwarf companion of HD 165141 has a temperature of about 35,000 K. Spectral types and rotational velocities have been determined for the three giants and distances have been estimated. These three systems and 39 Ceti are compared with the barium …
Chromospherically Active Stars. X. Spectroscopy And Photometry Of Hd 212280, Francis C. Fekel, Jared C. Browning, Gregory W. Henry, Mary D. Morton, Douglas S. Hall
Chromospherically Active Stars. X. Spectroscopy And Photometry Of Hd 212280, Francis C. Fekel, Jared C. Browning, Gregory W. Henry, Mary D. Morton, Douglas S. Hall
Information Systems and Engineering Management Research Publications
The system HD 212280 is a chromospherically active double lined spectroscopic binary with an orbital period of 45.284 days and an eccentricity of 0.50. The spectrum is composite with spectral types of G8 IV and F5-8 V for the components. An estimated inclination of 78 +/- 8 deg results in masses of 1.7 and 1.4 solar mass for the G subgiant and mid-F star, respectively. The distance to the system is estimated to be 112 pc. Photometric observations obtained between 1987 November and 1992 June reveal that HD 212280 is a newly identified variable star with a V amplitude of …
Lithium And Rapid Rotation In Chromospherically Active Single Giants, Francis C. Fekel, Suchitra C. Balachandran
Lithium And Rapid Rotation In Chromospherically Active Single Giants, Francis C. Fekel, Suchitra C. Balachandran
Information Systems and Engineering Management Research Publications
The rotational velocities presently obtained via spectroscopic observations of a group of moderately rapidly rotating, chomospherically active single giants indicate that Gray's (1989) rotostat hypothesis requires modification. Their rapid rotation appears to be due to high Li abundances, and results in increased chromospheric activity. A scenario is projected in which the surface convection zone reaches the rapidly rotating core just as a star begins its first ascent of the giant branch, and dredges both high angular momentum material and freshly synthesized Li to the surface.